The present disclosure relates to microwave popcorn and its preparation. That is, the disclosure concerns arrangements that involve unpopped kernels of popcorn which are prepared and presented in a manner such that they readily pop, upon exposure to microwave energy in a microwave oven.
In many conventional microwave popcorn systems, the popcorn is packaged in a flexible, foldable, typically paper, construction with: oil/fat; flavoring, if desired, for example salt; and, optionally, coloring. When the package is placed in the microwave oven, the popcorn is popped in the presence of the oil/fat and the flavoring/coloring is distributed over the popcorn.
A typical such system is used in the consumer product ACT II.RTM. Buttered Popcorn, available from Golden Valley Microwave Foods, Inc. of Edina, Minn., the Assignee of the present invention. A typical such product contains, in each bag, about 70-80 grams of popcorn and about 30 grams of an oil/fat slurry. The oil/fat slurry includes about 9% salt by weight, with the remainder primarily comprising the fat/oil, and some butter flavor (about 2% butter flavor, including the weight of the carrier for the flavor, typically maltodextrin).
It is important that such microwave popcorn products be substantially shelf stable. In these types of systems, "shelf stability" is generally associated with the following principal characteristics.
(1) Some acceptable, preferably very low level of wicking or leakage of oil/fat from the inside of the package, during storage and handling at normally encountered ambient temperatures; PA1 (2) An acceptably low level of moisture loss from within the popcorn kernels, during storage and handling; PA1 (3) A polyunsaturated oil presence sufficiently low that undesirable levels of oxidation do not occur during storage.
In general, loss of moisture from the kernels is typically associated with less efficient and effective popping, and loss of oil/fat is associated with increased scorching, less flavor distribution and a less efficient popping process.
In general, in conventional systems of the type previously described, control of moisture loss and shelf stability are, in part, obtained through the selection of a particular type of oil/fat and the utilization of selected, preferred, amounts of the oil/fat material. More specifically, the typical oil/fat component of common, conventional microwave popcorn charges is a solid, partially hydrogenated soybean oil. Such a material has a melting point (Mettler Dropping Point) of about 100-105.degree. F. and a SFI (Solid Fat Index-AOCS Cd 10-57, Dilatometric) typically as follows:
______________________________________ Temperature (.degree. F.) Solid Fat Index (SFI) ______________________________________ 50 53-57 70 38-42 92 14-18 104 3.5 maximum ______________________________________
One such material, available from Cargill Refined Oil, Minneapolis, Minn. 55440, as a microwave popcorn shortening, has a free fatty acid (oleic) content of 0.04% maximum (AOCS Ca 5a-40), and a moisture content (AOCS Ca 2c-25, Karl Fisher Method) of 0.10% maximum. The peroxide value is about 1.0 Meq/Kg maximum (AOCS Cd 8-53).
This product contains a fatty acid content, by weight, of about: 10.2% C16 unsaturated; 10.2% C18 unsaturated; 40.2% C18 monounsaturated (oleic); 34.3% C18 monounsat. trans(elaidic); 1.7% C18:2 cis(diunsaturated); 2.3% C18:2 trans(diunsaturated); 0.1% C18:3 unsat. (cis); 0.1% C20 saturated; and 0.3% C22 saturated. Thus it contains about 20.8%, by weight, saturated fatty acids; about 74.5%, by weight, mono-unsaturates (cis+trans); and about 4.1% polyunsaturates. The content of trans unsaturates (total) is about 36.6%.
Such a material is generally desirable for shelf stability since it is relatively solid under most handling conditions, for example storage at room temperature or even in warm environments. Since it is solid, i.e. has a relatively high SFI index, it does not readily wick into or permeate conventional greaseproof-type paper sheets of the type used in conventional microwave constructions. Thus, it does not readily leak from the systems, or wick through the systems, in use.
In addition, in conventional systems such an oil/fat is typically utilized in an amount, by weight, such that it has enough volume to substantially engulf or enrobe the popcorn kernels (i.e. about 27.sup.+ grams of oil/fat per 70-80 grams of unpopped kernels). This tends to trap the moisture within the kernels, and to inhibit loss of moisture from the kernels during storage. Because the oil/fat material sets up (solidifies) rather quickly during processing, and does not melt and flow substantially under normal handling (ambient) conditions, the kernels can remain engulfed within the oil/fat during storage, and less moisture loss from the unpopped kernels occurs.
In general, solid, partially hydrogenated soybean oil in the amounts indicated has been the oil of choice for many conventional microwave popcorn systems. Not only is the material associated with shelf stability, when used in conventional paper microwave popcorn packaging, but also it is associated with good flavor and texture, and does not substantially scorch or burn during the microwave popcorn process, even when in close thermoconductive proximity to microwave interactive constructions such as the microwave susceptors used in conventional packaging.
In addition, the oil/fat, during the microwave popping process, for conventional systems, is an important component in the distribution of flavoring/color over the popped kernels. In general, the flavoring and color is dispersed in the hot liquid oil/fat during the microwave popping process, and as the kernels pop and bounce around inside the bag, the liquified oil/fat splashes over them, distributing the flavor and colorant to the surfaces of the flakes. This presents the product with a desirable hue or color and desirable aroma. Also it is associated with relatively high flavor impact, since the flavorant is located on the outer surfaces of the flakes where it will be readily encountered by the taste buds of the consumer when the product is eaten.
In recent years, consumer interest in the nutritional values of snack foods, such as popcorn, has heightened. In many instances, consumers prefer to prepare their foods by means other than through the utilization of substantial amounts of oil/fat in the preparation process. This general consumer desire has been addressed by the microwave popcorn industry, through the development of "light" or "ultra-light" popcorn products.
Some approaches to presenting light or ultra-light products to the microwave popcorn industry, have simply involved the utilization of less of the same solid, partially hydrogenated, soybean oil as used in other products, per gram of unpopped popcorn kernels, in the microwave popping formulations. That is, typically the approach has involved the continued use of solid, partially hydrogenated soybean oil, but in lesser amounts. A typical such product contains about 6.5 to 7.5 grams of partially hydrogenated soybean oil per 77 grams of unpopped popcorn kernels, i.e. the oil being provided as a flavored slurry with the slurry provided in an amount of 9-10 grams per 77 grams of unpopped kernels. In general, the continued use of the solid, partially hydrogenated soybean oil has been associated with good shelf stability, with respect to wicking or leakage from the package, due to the solid nature of that oil/fat material. However, utilization of lesser amounts of the oil has involved less enrobing of the kernels, and thus a greater propensity for moisture loss. In some systems, this has been addressed by the utilization of better moisture barrier overwrap packaging, for the microwave popcorn products.
The utilization of lower amounts of fat/oil in conventional products has also been associated with a need for greater control of cooking time in order to avoid scorching. In some instances, it has also involved less effective distribution of flavorant/colorant, over the kernels.
In addition, completely satisfactory nutritional limits have not been achieved with these conventional systems.
Relatively recently, "no-added fat" microwave popcorn systems (i.e. systems which are free of added fat) have been developed. Such systems are described, for example, in U.S. patent application Ser. No. 08/198,892 filed Feb. 18, 1994, now abandoned; Ser. No. 08/391,437 filed Feb. 21, 1995, now abandoned; and Ser. No. 08/397,481 filed Mar. 2, 1995, now U.S. Pat. No. 5,585,127, each of which is incorporated herein by reference, and is owned by Golden Valley Microwave Foods, Inc. In general, such systems involve coating of the individual kernels, before packaging, with an adhesive composition including flavorant/colorant. Thus, the kernels are maintained in individual flowable form, each being coated and having flavorant adhered thereto. Essentially no oil/fat is added to the system, to facilitate cooking.
Such arrangements have been relatively effective. However, it has been found that, in general, some consumers prefer the mouth-feel, hue, aroma, and/or taste, associated with oil/fat. Thus, it is desirable, if possible, to develop an improved fat-containing, low-fat microwave popcorn system that is shelf stable, includes a sufficient amount of oil/fat for the satisfaction of certain consumer preferences and which also meets preferred nutritional guidelines.